It is known to inflate an inflatable vehicle occupant protection device to help protect a vehicle occupant in the event of a vehicle collision. One particular type of inflatable vehicle occupant protection device is an inflatable curtain that inflates from the roof of the vehicle downward inside the passenger compartment in the event of a side impact or a vehicle rollover. The inflatable curtain, when inflated, is positioned between a vehicle occupant and the side structure of the vehicle. A known inflatable curtain is inflated by inflation fluid directed from an inflator into the inflatable curtain through a fill tube.